The rebuilder is only for adding valid roms or to create sets from your current collection to another (e.g. other emu). The rebuilder only works if crc32 and size of roms match. The scanner is much more powerful for all kind of changes. Fixing sizes, checking chds, deep checksum analysis etc..etc...

So...when updating to a new version of MAME, I personally use the scanner to fix all problems and add the new sets via the rebuilder (i.e. drag & drop in the scan results window).

Roman Scherzer
ClrMamePro

Roman, I just read your Scanner & Rebuilder Dialogs so I could better understand the "Drag & Drop" feature that you speak of. I am still not clear on that since I didn't see any examples. Could you be more specific as to what you mean about how to "add the new sets via the rebuilder (i.e. drag & drop in the scan results window)"? Thanks!